Efficient, quick access to data is one of the driving forces behind the rapid increase in popularity of the World Wide Web and the Internet. However, until access to the Internet via portable devices such as cell phones or personal data assistants (PDAs) becomes more available, more reliable, and sufficiently low in cost, it will generally be preferable to provide access to needed data that are simply stored in the electronic memory of a PDA or other such portable computing device. A relatively large amount of data of interest to an individual can be stored in a few megabytes of memory in such devices. Indeed, so much data can be loaded into memory that accessing a desired portion of the data can be somewhat difficult using conventional browsing techniques or using an indexed data search.
The most logical way to organize data to facilitate rapid and efficient retrieval of desired facts is to first arrange the data in a rational hierarchical structure that is organized along the lines in which people typically think when “zeroing in” on a desired piece of information. It will generally be easier for a user to view a limited number of subjects at the highest level of the hierarchy, select one of the subjects that seems most relevant to the desired information, and then select a category under the selected subject that seems most relevant. These steps can then be repeated one or more times, enabling the access of successively lower levels of the hierarchy, and ultimately should yield the specific information being sought by the user.
While it is possible to organize data in such a logical hierarchical structure so that it can be readily located in the above-described manner, it can sometimes be more efficient to employ an alphabetically ordered subcategory index to locate the desired information. However, a topic that is selected from such an ordered index may be closely related to the desired information, but not include the actual data of interest. Also, note that a subcategory list displayed as a result of an index search may include subcategories that differ from a subcategory list displayed as a result of a hierarchical search.
An example can help to clarify the preceding point. In this example, the data in a database are arranged in a hierarchical relationship and stored in the memory of the portable device. These data include information relating to points of interest, travel, businesses, services, restaurants, etc, for a specific metropolitan city or region. Included under a top level is the subject “Business and Government.” Under that subject are second level categories that include the following: “Associations;” “Banks & Brokerages;” “Chambers of Commerce;” “Convention Info;” “Government Information;” “Legal and Courts;” “Major Employers;” and “Shipping and Supplies.” A person searching for a financial institution at which to apply for a loan might initially choose the category “Banks and Brokerages,” and then choose the next level subcategory “Banks” from a list of subcategories that also includes: “ATM's;” “Brokerages;” “Credit Card Companies;” “Credit Unions;” “Currency Exchange;” and “Travelers Checks.” From the list of banks displayed when this subcategory is selected, the user could then choose a desired bank, causing the display of an address, telephone number, and other pertinent information, or the user could move back to the display of subcategories and choose the subcategory “Credit Unions” to list the available credit unions in the region. Thus, the hierarchical categorization of data enables the user to search through the available categories and find the desired data relatively efficiently, but more importantly, it enables the user to choose from among related subcategories so as to ensure that the desired information is readily displayed.
Alternatively, a user may prefer to search for information using an index that lists subcategories alphabetically. In the prior art, selecting a topic such as “Banks” would only result in a list of the banks included in the data being displayed. The hierarchical relationship of the subcategory “Banks,” relative to the categories and subjects in the example set forth above, would not be evident from such a list. Clearly, it would be preferable to display the hierarchical category and subject above the subcategory “Banks,” since a user would then more readily be able to expand a search into a related subcategory, such as “Credit Unions,” to find useful information related to the original index subcategory that was selected. However, since a typical prior art index search does not display the hierarchical levels above a selected index subcategory, the benefits of the hierarchical categorization of the data would be lost by making an index search.
The need to retain and display the hierarchical relationship of data being accessed through an indexed search is particularly relevant to data accessed with a portable device such as a PDA, since such devices have relatively small display screens and can only display a few lines of information at one time. By enabling a user to access hierarchical data through either a hierarchical search or an index search, while retaining and displaying the hierarchical relationships of the data accessed via the index search on the display screen, a user will be able to readily determine if other related subcategories should be viewed to best identify information of interest to the user.